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Discussion Starter · #1 ·
96 zx-6r, sat for a while. Took the carbs apart and cleaned. Reinstalled, did a carb sync and this part throttle problem came about when I started it. Also makes a funny sound like not all cylinders are firing, butget past part throttle and it sounds great and runs like a banchee. Low rpm doesn't have the problem. After the problem occured I played around with the pilot jet adjustment, to no avail. Same thing. Looking for Ideas on what to look for before I tear into it again.

Thanks in advance.

Brian,

Do it right. Or do it twice. (like I'm doing now)
 

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Hesitation at small throttle openings usually means your float level is too low. Just remember that when you set them up the carbies are upsidown so the lower the number the richer the mixture. HTH
 

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b_dub,

zix6r posted a topic today about a similar 6K hesitation. The cause was some of the small o-rings that seal the vacuum port between the carb body and the plastic vacuum diaphragm covers were misplaced when the carbs were dissassembled. The o-rings sometimes stick to the diaphragm cover when you remove it and then fall off as you turn it over to remove the slide spring. Good luck!
 

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Discussion Starter · #4 ·
thanks for the pointers guys, I'll be checking both tonight. It isn't going to be 120 degrees in my garage finally.
 

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Discussion Starter · #5 ·
allrighty then. Once I get these damn carb issues fixed I'm selling it and getting a fuel injected bike.

So, here is some more background on the problem, that I omitted because I thought it irrelevent. But apparently not.
In the initial dissasembly and cleaning I lost 1 of the stock main jets, dropped it and it disappeared. Since I had a jet kit laying around that I've been meaning to put in for years, I checked it to see if it had 1 close. K&N jet kit and it had the 150 jet I was looking for, yeh, is what I thought at the time (found out in another post that the stock jets are different then the dynojet jets). This leads into the 6k up part throttle problem originolly posted about.

So I learn that and I complete the Stage I jet kit install. Good news, no hesitation from 6k up. It's running a little ruf in that range but that's probalby since I didn't sync that carbs????? Now it's running like crap from idle up to 6k(part throttle again). Did I mention what a difference in power. I was impressed (yoshimura bolt on race pipe, w/ a Uni air filter).

What do I adjust to fix the low rpm crap?

Thanks again, sorry for the long post. But getting frustrated.
 

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Discussion Starter · #6 ·
If I play w/ the needle settings which way would I go? up or down.
Is the pilot adjustment going to do anything down that low?
 

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You probably have clogged idle or pilot jets (same jet. Take them out and clean with a really good solvent because when the gas sits for a while the additives and varnish cruds them up and sticks like gllue to the orifices. Good luck.
If you adjust the needle put the clip closer to the tapered end.
 

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Discussion Starter · #8 ·
thanks thack,

I cleaned the crap out of all the jets, and checked all the orifaces. I don't think its clogged, but I'm at a loss so I'll check again.

Just to clarify what I think I understand:
Idle jet is for idle (duh), pilot is just part throttle and main is everything else. Is my understanding correct?

What does the needle adjust? is it a fine tune for the pilot jet? so further from the pilot, means more fuel?

thanks for helping out a dummy. (I do know alot about fuel injection, my 65 mustang has it:D).
 

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The idle and pilot jet are the same. The air screw adjusts the idle jet to some extent. The idle jet affects up to 1/4 throttle position. Too small an idle jet and you have very hard starting and a big miss when you open the throttle. Too much jet and you foul plugs with the choke on.
The needle affects from 1/8 to 7/8 throttle position. Your right, the further the needle from the MAIN jet the more gas that comes from the main jet. The needle"tunes" the main jet orifice. That needle goes right down into the main jet. That's why needle diameter, taper and position are critical for perfect tuning.
The cutaway of the slide affects partial throttle opening up to 3/8 position.
The main jet affects from 3/4 to full throttle. It flows fuel down low but the actual position where it is most crucial is close to full throttle.
Every jet overlaps the affected throttle position before and after it.
So if you need more fuel when you open the throttle try to get the needle up further out of the main jet. If the choke helps you at this postion, put your clip down one notch on the needle.
If you have hard starting and need the choke on until it fully warms and dies when you open the throttle, use a bigger idle jet. The factory leans out these bikes at the factory and when the bike is "broken in" most of the time it needs more fuel. Remember our carbs don't have an accelerator pump so getting enough fuel off idle is tricky.
If your plugs are black and the bike runs worse with the choke on then you have too big of a jet.
 

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Discussion Starter · #10 ·
thanks again Thack,
with a better understanding of how it works will make my experiments to see what works go smoother.

So, the K&N kit came w/ washers and instructed to put them on the top of the clip(whether or not I got the top correct I'll be finding out, I'm sure I did that wrong). So to really fine tune the needle position you can play w/ the washers and/or clip to get the "perfect" needle position. As light bulbs go on in my head.

greatly appreciated.

Do it right, or do it twice. Or in my case take the tank off about fifty times.
 

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Discussion Starter · #11 ·
Thack,
Got it running a lot smoother in most areas, but in low rpms w/ 1/8 or less throttle I have no power, I have to give it a significant amount of gas to get it going.
Should I move the needle further, or play w/ the pilot adjustment, or get a differernt idle jet?

Thanks again.
 

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If the choke helps your situation then go with bigger idle jets. Sometimes you can turn the air screw but it sounds like it's falling flat on it's face. Raisng the needle more may help. It can't hurt and you can always put it back if it gets worse.
If the choke kills your bike at idle or makes your big bog worse then turn the air screw and/or get smaller idle jets.
You should have #35s. I'll be taking out my #38s Monday or so to put bigger ones in my ZX-9R. You can have them for $2 each + shipping ($1.70). I have to move this weekend or I would do it sooner. Or you can go buy them at a few places.
 
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